Carburetors are used to provide the combustion fuel requirements for a wide range of two-cycle and four-cycle engines including hand held engines, such as engines for chainsaws and weed trimmers, as well as a wide range of marine engine applications. Diaphragm type carburetors are particularly useful for hand held engine applications wherein the engine may be operated in substantially any orientation, including upside-down. These carburetors utilize a fuel-metering diaphragm which is operative to control the delivery of fuel from the carburetor regardless of its orientation. Additionally, some carburetors utilize a diaphragm type fuel pump which is responsive to engine pressure pulses to draw fuel from a fuel supply and to deliver fuel to the fuel metering assembly under pressure. The fuel pump diaphragm defines a fuel chamber on one side which receives liquid fuel and a pressure pulse chamber on its other side in communication with the engine to receive pressure pulses which actuate the fuel pump diaphragm.